1. Field of the Invention
The invention relates to electrical conductor arrangements for high speed transmission, and particularly to the arrangements for use with differential pair(s) to eliminate the crosstalk thereof.
2. The Related Art
Crosstalk is the concern in high speed transmission. In fact, the concept of xe2x80x9cdifferential pairxe2x80x9d of the conductors to eliminate the crosstalk between the adjacent conductors are popularly used in the industry field. Understandably, the basic theory of the differential pair arrangement is based on the crosstalk impact from the same xe2x80x9caggressorxe2x80x9d source to the respective xe2x80x9cvictimxe2x80x9d conductors of the differential pair being the same with each other when the two (victim) conductors of the victim differential pair are respectively equally spaced from the same xe2x80x9caggressorxe2x80x9d source. Under this situation, the undesired crosstalk noise signal due to the same xe2x80x9caggressorxe2x80x9d source may be theoretically eliminated with the subtraction calculation. This phenomena is generally based on the assumption that the victim differential pair is spaced from the aggressor source with a significant distance while the internal distance between the two conductors of the victim differential conductors internally is relatively small. Understandably, regardless of the circuits on the printed circuit board, the contacts in the connector, or the wires of a cable, the distance between the differential pair of victim conductors and the aggressor source is relatively small, so that the induced crosstalk from the same aggressor source to the two respective conductors of the victim differential pair will be obviously different. This is an inherent shortcoming.
For example, U.S. Pat. Nos. 5,647,770, 5,971,813, 6,017,247 and 6,120,329 disclose some approaches to eliminate the crosstalk among the differential pairs of conductors. Obviously, the way these approaches used is generally to intentionally oddly deflect/off some portions of the corresponding contacts of the modular jacks to be coupled/close to other corresponding contacts so that the crosstalk measured at the ends of the contact tails, via which the modular jacks are mounted on the mother board, may be reduced. Understandably, such a method requires complicated calculation and/or plural try-and-errors. Additionally, such complicated/odd configurations of the corresponding contacts make it difficult to manufacture/assemble the modular jack. Moreover, due to such offset/deflection arrangement of some contacts, the lengths of the electrical paths of the respectively contacts will be different, thus resulting in the skew effect which is also not desired by the electrical circuit design.
U.S. Pat. Nos. 3,761,842 and 6,057,512, and the copending application Ser. No. 09/535,426 filed on Mar. 27, 2000 with the same assignee, disclose the similar approach in another application, i.e., the cable field, where the differential pair of wires are twisted for eliminating the crosstalk from the adjacent wires. Understandably, the twisted arrangement of the differential pairs makes it difficult to manufacture the whole cable, increases the lengths of the electrical paths, i.e., increasing the resistance thereof, and also results in the improper skew effect.
Yet, the similar approach in another field can be referred to FIG. 1 disclosing the differential pairs of conductors/traces are applied on the printed circuit board, wherein a ground circuit is disposed between every two adjacent differential pairs of signal conductors for eliminating the crosstalk therebetween. Understandably, the placement of plural ground circuits between every adjacent two different pairs of signal conductors will occupy significant space on the printed circuit board, thus opposing the miniaturization trend of the electrical industry.
Anyhow, disregarding the foregoing disadvantages of the existing approaches used in the different fields, other than the crosstalk concern another important issue for the high speed transmission is impedance matching/consistency requirement wherein the impedance corresponds to the associated inductance and capacitance thereof. The inconsistency/un-matching of the impedance along the electrical path may create the reflection of the signal and thus jeopardize the quality of the signals which is looking for the required so-called eye pattern of the signal configuration, i.e., the signal configuration being not fallen within the minimum region of such an eye-pattern for assuring transmission stability and reliability thereof. Understandably, the odd deflection used in the modular jack contacts and the twisted pair of the wires may result in impedance inconsistence along the electrical path because of changeable/inconsistent distance between the differential pair of victim conductors and the corresponding aggressor source. Therefore, the quality of the signals can not meet the preferable eye pattern. Additionally, in the differential pair application, the two conductors of each victim differential pair ideally should be arranged as close as possible so as to try to achieve the close/similar magnitude of the induce crosstalk noise for elimination by subtraction. While the internal distance between two conductors of each differential pair is also an important factor for controlling the impedance thereof. Moving closer to each other may result in the un-matching or incompatible impedance along the transmission path. In other words, most of time there is a conflict situation between the reduction of the crosstalk and the consistency of the impedance because of the inherent structure limitations and electrical characters. In other words, it is required to scarify some portions of at least one of these two factors for implementation.
Moreover, in all the aforementioned three type application fields, the crosstalk can not efficiently or ideally eliminated, and thus for the far-end crosstalk, the peak value of each individual victim conductor may not be in phase due to the propagation delay skew. In other words, because of the possible propagation delay skew, the induced crosstalk of each differential pair can not be symmetrically eliminated with each other. Under this situation, the actual differential far-end crosstalk may be higher than the difference of the peak value.
Therefore, an object of the invention is to provide a differential pair arrangement of the conductors where the plain, systematic and scientific arrangement is presented under a controllable and predictable sense.
Another object of the invention is to provide an arrangement where the crosstalk can be efficiently eliminated or even disappear at each single moment so that the crosstalk of either the far-end or the near-end is expectedly desirable zero.
Yet another object of the invention is to provide an arrangement where the crosstalk can be zeroed down while without jeopardizing the compatibility of impedance thereof.
According to an aspect of the invention, an arrangement of differential pairs of conductors includes two pairs of conductors intersect with each other at a right angle to form a cross-like configuration thereof wherein the distance between the respective victim conductor and one of the adjacent differential pair of aggressor conductors is equal to that between the same respective victim conductor and the other of the adjacent differential pair of aggressor conductors so that the crosstalk imposed on such a respective victim conductor due to the adjacent differential pair of conductors can be almost zeroed down at every moment, thus assuring no crosstalk at either far-end or near-end of such a victim conductor.
Another feature of the invention is that the respective victim conductor can be a single-ended type rather than a differential pair type wherein such a victim conductor may be moveably disposed at any position which is located in a plane equidistant with the differential pair of aggressor conductors.
Another feature of the invention is to almost zero down the crosstalk along the whole length of the victim conductor whereby the impedance thereof can be adjusted to meet the impedance of the next connecting part around the two ends of the victim conductor without jeopardizing the crosstalk thereof.